Earthquake resistant curtain walls with suspended glazed panels

ABSTRACT

This invention refers to curtain walls capable of resisting the seismic forces of major earthquakes without breakage of their glass panes and without deformation or distortion of their structure. The above can be achieved through the operational separation of the curtain wall of each storey from those of adjacent storeys, by formation of a sliding line on the top of the windows ( 2.3 ), through the mutual hooks of suspension of the windows ( 6.3, 6.10 ) so that the displacement of the one storey to be independent from the others. The structure of the curtain wall of each storey confined only to the fixed part of the curtain wall of the storey and consists of the uprights ( 3.1 ), the sill-beam ( 3.2 ), the lintel-beam ( 3.3 ) and the attachments ( 3.4 ). There are no uprights in the region of windows. The uprights of the structure of curtain wall of each storey at no case are touching the glass panels. The interstorey drifts ( 6 ) are in all directions absorbed by the suspension joints of the windows ( 7.5 ) and ( 7.6 ) and the angle profiles ( 10 ).

This invention refers to the production, fabrication and erection of curtain walls with suspended glassed panels capable of resisting to the seismic forces of major earthquakes without breakage of their glass panes and without deformation or distortion of their structure.

We are all aware of the extent of devastation caused by major earthquakes to the constructions and particularly to the buildings, as well as of the impact of such devastation on a personal or national level resulting from the loss of human lives and from the material and economic damages.

This is the reason for which such great numbers of Scientific Organizations, Universities, Research Centers and Institutes are involved with the seismic protection of buildings, aiming mainly at the construction of buildings whose the structural elements are capable of resisting the strains of major earthquakes, thus restraining the risk of collapse.

The problem of effectively reducing the seismic risk by the construction of earthquake resistant buildings is particularly complex, since it is affected by large numbers of parameters and many other factors.

On the one hand, there is the earthquake with its characteristics (range, distance, direction, depth of epicenter), which, combined with those of the soil on which the building is founded (composition, condition, moisture) result in the earthquake magnitudes charging the building (acceleration, speed, duration, frequency of vibration). On the other hand, there is the building itself receiving the seismic forces and resisting to them depending on the characteristics of its structure (building geometry, form, mass, structural elements arrangement, rigidity, fundamental period of vibration etc.).

A building's structure constitutes its main load bearing elements. It is its bearing constitution directly receiving all seismic forces and reacting to them. The degree of the building's survival over an earthquake depends on its reaction and its overall dealing with such forces.

However, the building structure is supplemented by all additional non structural components adjusted to the structure and reacting in parallel with it, depending on their specific characteristics. It is widely accepted that the functional capability of the building and its classification as habitable or not frequently depends on the extent of damage sustained by such additional building components, irrespectively of the fact that the structure may have been unharmed.

Among the non structural components of a building the most important are considered to be the glass curtain walls of the façades, which compared with all other components, present the greatest degree of vulnerability during an earthquake.

This high vulnerability of glass curtain walls is due to the fact that glass panes are unable to follow the deformations imposed to the building structure by seismic forces in the course an earthquake and to adjust to the interstorey drift. More specifically, they are unable to adjust to displacements parallel to their surface, since the glass panes cannot deform to this direction.

However, and irrespectively of the fact that the building structure may have survived undamaged after an earthquake, as already mentioned, the frailty of glass panes particularly against hits and pressure applied onto their edges, leads to them being first among the façade components that are destroyed.

The elements more strained by the seismic forces due to seismic acceleration ant the interstorey drift are the attachments of fastening the curtain wall on the structure of the building.

Descriptive figure of the deformation and the interstorey drift (δ) caused to the building structure between two adjacent storeys in the course of an earthquake are presented on FIG. 1A. It shows the floor slab of the storey referred to (1.1), the roof slab of the said storey or floor slab of the storey above (1.2) and the columns of storey (1.3) under conditions of calm (no tremor). FIG. 1B presents the deformation of elements and the interstorey drift (δ) between slabs of the two storeys (1.4) under conditions of seismic impact.

FIG. 1C presents the same section of the building structure along with the structure of the curtain walls provided in ordinary constructions, under conditions of calm (no tremor), while FIG. 1D refers to the same elements as above under earthquake conditions, during which the structure of the curtain walls keeps up with the deformation of the building structure. FIG. 1E presents the same structure as that of 1C, with the addition of glass panels, under conditions (no tremor), while FIG. 1F refers to conditions of seismic impact and shows that the glass panels fail to keep up with the deformation of the curtain walls structure supporting them, with the result of their breakage.

The said structure of the curtain walls and its performance under earthquake conditions is presently adopted by all existing international glass curtain walls systems having a structure that consists of vertical beams (uprights) running throughout the height of the curtain walls as continuous beams and of short horizontal beams (cross-beams) fixed in-between the vertical ones. The glass panes or panels of the curtain wall are fixed in full contact with and supported by the vertical and the short horizontal cross beams.

A relevant survey conducted in the United States of America has concluded that it is possible, with the existing systems, to deal with minor drifts (δ) by increasing the margin left between glass panes and aluminum profiles or by rounding up the corners of glass panes. However, such solutions are deemed to be unsatisfactory in the cases of major earthquakes, in which requirements for margins between panes and frames are much heavier, particularly in buildings of steel structures.

These weaknesses are lifted by implementing the present invention, which ensures that glass panels remain unaffected by the interstorey drifts of the building floors in the course of an earthquake and not only that the glass panes remain unbroken, but the entire curtain wall resumes its original position without transformation or alteration of its structure as a result of the tremor. This has been verified by way of a laboratory test conducted at the Lab of Seismic Technology of the National Technical University of Athens on an integrated curtain wall set on the bench of a seismic simulator on Jun. 16, 2006 with fully closed windows on the curtain wall. The test was repeated with open windows on the 27^(th) of the same month. It proved fully successful in both cases, as attested by the attached certificate of the laboratory, preceding the issuance of the final report and certificate, which is expected in two-month time.

To be earthquake resistant, a glass curtain wall should be capable of absorbing the entirety of interstorey drift occurring in all directions between the adjacent storeys, while its components should be capable of withstanding, without any permanent deformation, the accelerations (g) developed in the course of the earthquake, irrespectively of the tremor spectrum.

This capability should be characteristic of all glass curtain walls at any level and in any direction, of corner walls at any corner, edge or setback, corner walls between buildings, as well as of curtain walls carrying unified glass panels from one floor to the other floor.

In addition, the seismic resistance of the glass curtain wall should not affect its functional capacity or its air- and water-tightness and it should not reduce its strength against wind pressure and other external forces after the termination of the earth tremor.

All the above may be achieved by way of a functional separation of the glass curtain wall of each storey from those of adjacent storeys, upper or lower, in a way ensuring that the drift of the curtain wall in each storey will be independent from those of curtain walls over the other storeys.

To this effect, the glass curtain wall over each storey is ideally divided (FIG. 2A) into two distinct sections (2.1) and (2.2) via a horizontal division line drawn all along the storey façade at the level of the window lintel (2.3).

Each section (2.1) and (2.2) consists of two parts: the firm part including the structure of the curtain wall over the specific storey, along with the firm glass panels (2.4) fixed on such structure (spandrel), and the part of the windows over the storey (2.5).

The two parts (2.4) and (2.5) run all along the storey and are interconnected in a way ensuring their joint cooperation in achieving earthquake resistance as a unified section (2.1) or (2.2), while allowing the window autonomy along with the capacity of windows to operate as open ones throughout the length of the storey, FIG. 2B (2.6).

FIGS. 3A and 3B present sections of the structure of a two-storey glass curtain wall, one at the storey floor slab, FIG. 3A, and the other at the floor slab of the storey above, FIG. 3B, both having as main components the uprights (3.1), the horizontal beams at each storey (3.2) and (3.3) and their attachments (3.4).

The uprights (3.1) carry over their tops and support the horizontal beams of each storey (3.2) and (3.3). Their height corresponds to the height of the structure of each storey and they are fixed onto the floor slab of the storey to which they belong by means of the attachments (3.4) in the form of cantilevers protruding on either side.

The supports (3.4) constitute the joint between the structure of the glass curtain wall and that of the building and are capable of assuming all forces generated by the earthquake, together with the other forces due to dead loads and wind pressures.

Among the horizontal beams (3.2) and (3.3), the beam (3.2), as shown in FIG. 3A, belongs to the structure of the storey referred to and constitutes the sill-beam of the storey windows supporting the lower side of such windows (2.5), as well as the beam from which the storey fixed glass panels (2.4) are suspended, while the beam (3.3), as shown in FIG. 3B, belongs to the structure of the storey above and constitutes the lintel-beam of the storey windows from which the storey (2.5) windows are suspended and which supports the lower side of fixed glass panels over the storey above.

With the structure arrangement described above, the uprights (3.1) are in no contact at all with the glass panels. This, therefore, makes possible their fabrication not only from aluminum sections, but also from steel sections such as IPE, U, Z or from hollow sections, which offer better and more economic solutions to the increased structural requirements of earthquake conditions.

In order to ensure the desired controlled rigidity at the joints of the uprights with the horizontal beams of the structure, it is recommended to apply the unitized construction system, i.e. prefabricated panels that may be transferred onto the works site and suspended from prefixed calibrated supports.

FIGS. 4A and 4B show the prefixed supports on the storey floor slab (4.4), along with the prefabricated panels of the unitized system (4.1). These include the structural elements supplemented by the usual cover materials, such as gypsumboards or cementboards or other similar material (4.2), as well as by interim insulation materials, such as boards of mineral wool or other similar material (4.3), along with all necessary components of flexural stiffness (4.5).

As shown on FIGS. 3A, 3B and 4A, 4B, no uprights are provided in the region of the windows. Thus, the structure of each storey is confined to its fixed part (spandrel), fixed onto its slab, which it follows in all earthquake displacement.

This means that the structure of the glass curtain wall of each storey follows only the displacements of the slab of the storey to which it is fixed. Therefore, it does not affect or is not affected by the displacements of the structure of adjacent storeys, above or below, from which it is independent.

FIG. 5 presents a general vertical section of the glass curtain wall covering three storeys, showing the fixed sectors of the storeys (5.1), (5.2), (5.3), with their fixed part (5.4) containing also the structure of each storey, and also with the part of the windows (5.5). FIG. 5 shows the lower horizontal sill-beams (5.6) of the windows, identical over all storeys, from which fixed glass panels of each storey (5.4) are suspended and which support the lower side of the storey windows. It also shows the upper horizontal lintel-beams of the windows (5.7), identical over all storeys, from which the windows of each storey are suspended and which support the lower side of the fixed glass panels of the storey above.

With specific reference to the upper horizontal beam (5.7), it is noted that this is the beam from which the windows of the storey referred to are suspended. However, it always belongs to the structure of the storey above, with the exception of the case of a glass curtain wall over the top storey, in which the beam is directly supported by the storey roof slab and belongs to the same storey. The same thing applies to the lowest/bottom storey of the glass curtain wall, in which case the beam rests directly on the storey floor slab.

In addition to the above, the horizontal beam (5.7) constitutes also the beam establishing, via the window suspension line, the line of ideal separation of the fixed sectors of the curtain wall over each storey (5.1, 5.2), along with the sliding line between them.

FIGS. 6A, 6B present at a larger scale the fixed sector (6.1) of a storey corresponding to (5.1) in FIG. 5 and show its two parts: the fixed part (6.4) and the part of the windows (6.5). The part of the windows (6.5) lies between the fixed part (6.4), a section of the fixed part of the storey (6.1) and the fixed part (6.4) of the fixed sector (6.2) of the storey above, to which belongs the horizontal beam (6.7), from which the storey windows (6.5) are suspended.

The hanging up of windows is continuous throughout the length of the storey and is achieved through the introduction of double mutual hooks (6.9 and 6.10). Of these, hook (6.9) is provided on the aluminum profile (6.7) of the upper horizontal beam-lintel of the storey windows, while hook (6.10) is provided along the upper horizontal profile (6.11) of the frames of glassed panels of the storey windows.

An insert (6.3) is provided in-between the double mutual hooks (6.9) and (6.10), of a material having a low coefficient of friction, polyamide or teflon or other similar. The insert creates the division and sliding line between the firm sectors of the storey (6.1 and 6.2) in a direction parallel to the surface of the glass curtain wall.

The sliding line (6.3) acts at the same time as a rotation line of the hook (6.10) for opening of the windows. This means that, at each storey and throughout the length of the storey, the glass panels in the region of the windows are opening windows.

All suspended windows through the double mutual hooks terminate with the lower horizontal profile of the frames of their glass panels (6.12) over the lower horizontal beam-sill (6.6) of the storey windows. The windows are tied and fixed onto the sill beam (6.6) in a manner ensuring that the two parts, firm part and windows, operate together as a unified sector (6.1), which cooperates under earthquake conditions with the respective sector of the storey above (6.2) via operation of the sliding line (6.3). As a result, the displacement of sector (6.1) is not affected by the displacement of sector (6.2). By extension, and since the same relationship of cooperation stands also with the fixed sector of the storey above, the drift of the glass curtain wall over one storey does not affect nor it is affected by the drift of the curtain walls of adjacent storeys.

As regards fixed glass panels (6.4) at each storey, their hanging is effected from the lower horizontal beam-sill of the storey windows, also by means of hooks. One of these hooks (6.13) is provided throughout the length of the lower horizontal beam-sill of the storey (6.6), while the other (6.14) is provided over the upper horizontal profile of the frame of fixed glass panels (6.15). The fixed glass panels are made firm through the use of other hooks. One of the latter (6.17) is provided throughout the length of the upper horizontal beam-lintel of the windows of the storey below (6.7) and the other (6.18) is provided over the lower horizontal profile of the frame of the fixed glass panel (6.16).

A rubber insert (6.19) is provided in-between the two hooks serving the hanging up and the fixing of fixed glass panels onto the structure of the glass curtain wall. The insert shall have a high coefficient of friction, while a stronger locking up of the fixed glass panels onto the structure is achieved through the use of bolts for tying up at point (6.20).

The setting up of the glass curtain wall described above allows a freedom of drifting in all directions. The possibility of absorbing the relative interstorey drift (δ) in a direction perpendicular to the surface of the curtain wall is quite high, depending also on the height of the windows. This is due to the hinges, one along the line of hanging up of the windows and the other one through the hardware of fixing the windows onto the horizontal beam-sill of the windows (6.21, 12.2, 12.3).

FIG. 7A presents a vertical section of the glass curtain wall in a state of calm, while FIGS. 7B and 7C refer to earthquake conditions with a seismic direction perpendicular to the surface of the curtain wall. The latter Figs show the hinges (7.5, 7.6) and the interstorey drift (δ) (7.7).

As deducted from FIG. 7, in the course of an earthquake, the structure of the glass curtain wall and the fixed glass panels attached to it (spandrel), as well as any other component fixed onto the structure of the curtain wall, remains firm in a direction perpendicular to the surface of the curtain wall. All drifting is assumed and absorbed in the region of the windows.

However, and if the glass curtain wall is to be fully earthquake resistant, the same thing should happen in all other directions. To this effect, whenever the direction of the earthquake is parallel to the surface of the curtain wall, which is the case of major problems on an international scale, the present invention offers a full solution.

As previously described, the line of suspending the windows constitutes a dividing and also a sliding line between the fixed sectors of the glass curtain wall on each storey. This is due to the introduction of an insert, of a material having a low coefficient of friction, between the double mutual hooks serving the hanging up of the windows (6.3). In this way, it is possible FIG. 8, for the two fixed sectors of the glass curtain wall (8.1) and (8.2) to slide freely between them, thus ensuring a free and independent displacement of the lower fixed sector in relation to the upper fixed sector of the curtain wall over each storey.

With this possibility, the lower fixed sector of the glass curtain wall (8.1), which follows the displacement of the floor slab of the storey referred to, is not affected by the displacement of the fixed sector of the curtain wall over the storey above (8.2), which follows the displacement of the floor slab of the storey above. By extension, the same thing occurs with the fixed sector of the curtain wall over the storey below. Therefore, the glass curtain wall over each storey remains unaffected by the seismic drifts (δ) of the adjacent storeys (8.6), thus the problem constituting the principal cause of breakage of the glass panes in an earthquake is eliminated.

Polyamide or teflon or other similar sliding matter with a low coefficient of friction is fixed over the extremity of the hook of the upper horizontal beam-lintels of the windows in a form commensurate to the hook end in a manner ensuring its firmness and safety.

In order to enable the sliding function between the two sectors, the two parts of each sector, fixed (8.4) and windows (8.5), should be strongly tied to each other over the horizontal beam-sill of the windows, so that the related seismic drift (δ) between the storey floor slabs (8.6) may be turned into a corresponding sliding (δ) (8.7) between the two sectors (8.1) and (8.2).

As already mentioned, the stability of each sector of the storey is achieved through the creation of a stable structure of the glass curtain wall in compliance with a unitized system, the implementation of strong fixing points capable of transferring the seismic forces with safety from the building structure to the structure of the curtain wall and vice-versa and also by fixing firmly the storey windows onto the sill-beam of the storey structure.

Naturally, the related drift (δ) between the storeys is transferred in a horizontal direction by way of the sliding line to the extremities of the glass curtain wall, where it terminates. A special angle of termination is therefore required to enable the drift to be absorbed.

There are several cases of terminations of a glass curtain wall. Most difficult among them is that of angle curtain walls, encountered in all independent buildings or buildings with a free perimeter. The difficulty lies in the fact that the angle of termination should be capable of absorbing the related drifts not only in the directions of the two sides forming the angle, but also drifts in any other random direction, as the directions of drifts generated by the earthquake are random and indeterminable, same as those generated by the performance of the building under the effect of twists.

In addition, the difficulty is aggravated by the fact that the drift parallel to the one side of the building structure entails a drift vertical to the other side, with the result of a conflict being created between the drifts of the curtain walls at the angles.

Thus, and with the purpose of dealing with the conflicting drifts at the angles of the buildings, the termination profile of the angles of the glass curtain wall should be capable of performing movements of a gyroscopic nature, if the curtain wall is to adjust parallel to such drifts.

As already mentioned and as shown on FIGS. 3 and 4, there are no uprights in the region of the windows of each storey. As a consequence, the same applies to the angles of the glass curtain walls. This makes it easy to form angle profile by directly joining the structure beams over each side of the storey.

FIGS. 9A, 9B, 9C show the formation of the angles of the glass curtain walls structure (9.1 and 9.2) by joining the horizontal beams, i.e. the sill-beam (9.3) and the lintel-beam (9.4), an operation performed by simply cutting the aluminum profiles in a diagonal direction and by joining them with the introduction of parallel blades capable of providing a firm and unfaltering angle, as required in each case (9.5, 9.6) and (6.22, 6.23).

As already mentioned, the construction of the angles of horizontal beams in the structure of the glass curtain wall implies that the entire structure of the curtain wall over each storey, both in its straight and angular sectors, is unified and follows in a unified way the displacement of the storey slab unto which it is fixed.

As a result, and with regard to displacement, all issues applicable to the sides are also applicable to the angles and, by extension, all relative interstorey drifts are assumed and absorbed in general in the region of the windows of each storey, irrespectively of whether the curtain wall is an angular one or not.

Furthermore, all the above imply the requirement for the sides of the window glass panels to be joined at the angle, also in the region of the windows. This will make it possible to ensure, on the one hand, a smooth absorption of relative drifts in all directions and, on the other hand, the operational joining of the two sides of the curtain wall. It will also make it possible to meet all requirements for air- and water-tightness, resistance of the curtain wall against wind pressures and safety of the glass panes, and also to maintain such requirements after the earthquake, by allowing the glass curtain wall to resume its original state, free of any deviation.

As already has been mentioned, all drifts are absorbed in the region of the windows. Therefore, the profile of the angle of the curtain is not continuous heightwise over the storey, but it is broken at the points of the horizontal beams on which it stands and it functions in collaboration with the end glass panels for the satisfaction of the above requirements. After all, the breaking of the angle profile at the points of the horizontal beams is imposed for reasons of tightness of the glass curtain wall. This is obtained in horizontal lines at the points of the horizontal beams by the insertion of the tight profile (6.24) over the sill-beam of the windows, and by the special form (6.25) of the hook profile of the lintel-beam (6.7) which ensures the required standard of tightness.

The profile of the angle shown on FIG. 10A was devised on the basis of these requirements. Combined with FIG. 10B, it shows, on a horizontal section, the relationship of the profile of the angle with the vertical profiles of the window side glass panels. FIGS. 10A and 10B present the main legs of the angle (10.1), which combined with the termination of the vertical profiles of the frames of the side window glass panels (10.6), which length of these legs defines the related drift (δ) of the glass curtain wall, which is absorbed at the angle. Furthermore, the legs of air- and water-tightness are shown, internally (10.2) and externally (10.3), with the same or even greater margins of drift, in combination with the terminations of the vertical sections of window frames (10.7) and of glass panels (10.8). The overlapping (10.11) of the angle legs (10.1) and of the terminations (10.6) takes into account the requirement for the terminations of the glass panels to overlap always the angle legs with the purpose of ensuring the smooth movement of the angle profile during the earthquake.

In order to provide protection against displacement in a diagonal direction of the building, the angle ends of glass panes are chamfered (10.9) proportionately to the anticipated drift in that direction (δ′) (10.10).

In the middle of the angle profile, a closed core (10.4) is provided, aiming at creating appropriate conditions of support of the angle profile at its ends and so to enable the follow-up of the drifts of the curtain wall over the angle.

With the purpose of enabling the absorption of drifts in all directions, the angle profile (11.1) is fixed at its ends at only two points. One at its top, FIGS. 11A, 11B, 11C, by suspension from the lower side of the angle of two upper horizontal beams-lintel of the storey windows (11.2) using an attachment in the form (11.3), which penetrates, through a cutting of the closed core, the upper end of the angle (11.4) and is held in place via a pin (11.5) allowing the free revolution of the angle profile at the top in accordance with the drifts of the structure of the storey above. The other fixing point lies at the lower end of the angle profile, FIGS. 11D, 11E, 11F, and is fixed onto the upper side of the angle formed by the lower horizontal beams-sill of the storey windows (11.6) by means of an attachment in the form (11.7) and by a pin (11.8) moving freely in all directions within a margin allowed in the attachment (11.9) for vertical movements.

The same angle profile is applied at the angle of fixed frames for reasons of architectural uniformity and of meeting in a unified way the requirements for tightness etc. as mentioned hereabove. The only difference being that the angle profile is fixed directly on the beams of the structure of the glass curtain wall, since the angle remains firm and steady on such structure.

In the case of a glass curtain wall of a single face/plane, the absorption of the drift in a direction parallel to the surface of the curtain wall is assumed by a profile of side edge in a form corresponding to half the angle profile, with edge sides at right angle and with legs of cooperation with the terminations of the end profiles of the frames of the window glass panels having a length commensurate to the anticipated drift (δ). In a direction perpendicular to the surface of the glass curtain wall, the drift (δ) (7.7) is absorbed by the free revolution at the joints (7.5, 7.6).

With regard to the unification of the two parts of the fixed sector, namely the joining of the structure of each storey with the storey windows, this may be achieved in a variety of methods, depending on the possible state of the windows before and during the earthquake.

If the windows remain closed (FIGS. 12A, 12B), as it usually happens in tall buildings, they will be fixed firmly on their sill-beam (12.1) by the use of attachments (12.2, 12.3) and (12.4, 12.5).

The bolt (12.2) with a square head is positioned by sliding into the incision (12.6) of the lower horizontal profile of the window frame (12.7), while the angle (12.3) is fixed firmly into the beam interior (12.1). Together, they hold and lock the windows against seismic forces perpendicular to their plane, forces corresponding to wind pressures, positive or negative. In parallel, and by way of their removal, they make it possible for the windows to function as opening windows in future, if required. At the same time and in collaboration with the joint along the window suspension line, they function as joints for absorbing seismic drifts (δ) (7.7) at right angle to the plane of the curtain wall.

Parallel to this, the attachment fork (12.4), firmly fixed onto the lower section of the window frame (12.7), in combination with the attachment pin (12.5), equally firmly fixed onto the sill-beam of the windows (12.1), bar the sideways displacement of windows in relation to the sill-beam (12.1), while in parallel they do not impede their opening.

Similar attachments, aiming at the same tasks and functioning in the same way as the fork (12.4), are fixed along the top of the window frames and at the points of vertical joints, FIGS. 13A, 13B, 13C. One of them (13.1) is fixed unto the upper horizontal profile of the frame of one window and has at one end the form of a small fork. The other (13.2) is fixed unto the same place of the other window, with its end termination entering its fork (13.1) to bar the shifting of one window in relation to the other, irrespectively of the fact that they are closed (FIG. 13A) or open (FIG. 13B). In this way, the space (groove) between the two windows (13.4, 13.5) remains stable, barring the risk of collision between the glass panels.

The two legs (13.1 and 13.2) are not in contact with the horizontal window suspension beam (13.3) and are fixed in such a way as to immobilize, in collaboration with the fork (12.4), the windows from any horizontal shifting in relation with the horizontal sill-beam on which they are held firm.

In the case that the windows are provided to operate normally as projected windows, FIGS. 14A and 14B, the attachments (12.2) and (12.3) are replaced by locks (14.1), which, combined with a pin (14.2), fully assume the seismic forces acting in a direction perpendicular to the surface of the glass curtain wall, corresponding to the negative wind pressures sustained by a glass curtain wall, while at the same time the attachments (12.4, 12.5, 13.1, 13.2) concerning the drifts parallel to the surface of the glass curtain wall remain unchanged.

Should, in the course of an earthquake, the windows occur to be open, the two parts will be unified, FIG. 15, by means of tough brackets serving to open and lock the windows (15.1), which, combined with attachments (13.1, 13.2), will immobilize the windows in whatever position they are caught. Thus, notwithstanding the fact that the windows are open, the sliding line at the double mutual hooks will function normally and drifts will be absorbed smoothly, as in the case of closed windows.

In the case that the panels of a glass curtain wall are unified from storey to storey or they are broken at each storey and are unified from the floor to the roof of the storey without a break in-between, the sliding line will function fully again with the suspension of glass panels from double mutual hooks, as in the case of the windows. In addition, the end angle profiles will function fully with the same fixing method, in which glass panels unified heightwise function as a fixed part of the storey, FIGS. 16A and 16B, and drifts are absorbed via the sliding line as before.

The difference in this case is that, when the glass curtain wall is continuous heightwise and the glass panels are unified from storey to storey (16.1), then the two horizontal beams of the case of the windows are unified into a single beam (16.2). The latter beam shall carry the features of both of them, a sill at the upper part (16.3) and a lintel at the lower part (16.4), double mutual hooks at the lower part (16.5), stabilization attachments at the upper part (16.6).

In the case that the glass curtain wall is broken from storey to storey, the glass panels are equivalent to very high windows, in which the upper horizontal beam lintel of the windows is positioned directly at the roof of the storey and the lower horizontal beam sill of the windows lies directly at the storey floor. Also in this case, the operation of earthquake resistance between storeys remains unchanged.

It is obvious that, in the above cases, in which the heights of the glass panels are increased, the dimensions of the components are adjusted to the new structural and dynamic requirements of the construction. 

1. Earthquake resistant curtain walls with suspended glassed panels are characterized by the fact that the curtain wall over each storey is separated functionally from the curtain walls of adjacent storeys, above and below, in a manner ensuring that the displacement of one of them will be independent from the displacement of the others, with the horizontal division line along the storey, the line of the top of the storey windows, which also functions as a sliding line for the curtain wall of one storey in relation with the curtain walls of the others.
 2. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirement 1, are characterized by the fact that, the curtain wall of each storey is ideally divided into distinct sectors (2.1) and (2.2), which run all along the storey with the line (2.3) as a division line, and each sector consists of two parts, the fixed part comprising the structure of the storey curtain wall and the fixed glass panels (2.4), and the part of the windows lining the same storey (2.5).
 3. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 and 2, are characterized by the fact that, the two parts of each sector (2.4) and (2.5) are interconnected in a manner ensuring their earthquake resistant performance as a unified sector (2.1) or (2.2), which constitutes the necessary precondition for the operation of the sliding line between storeys (2.3), providing at the same time the possibility for all windows to be opened, throughout the length of the storey (2.6).
 4. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 3, are characterized by the fact that, the structure of the curtain wall over each storey consists, of the uprights (3.1) which carry over their ends and support the horizontal beams (3.2) and (3.3), which are used for the suspension of the glass panels, the fixed panels (2.4) are suspended from the horizontal beam (3.2), while windows (2.5) from the horizontal beam (3.3), and by the attachments (3.4) through which the uprights are fixed firmly unto the floor slab of each storey, while the said attachments also assume all seismic forces generated in the course of an earthquake.
 5. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 4, are characterized by the fact that, among the horizontal beams (3.2) and (3.3), the beam (3.2) or (5.6, 6.6) belongs to the structure of the storey referred to and constitutes the lower horizontal beam of the storey, used for the suspension of the fixed glass panels of the storey (5.4, 6.4), and also the sill-beam of the windows (5.5, 6.5) of the storey while the beam (3.3) or (5.7, 6.7) belongs to the structure of the storey above and constitutes the upper horizontal beam of the storey, as well as the lintel-beam used for the suspension of the windows of the storey referred to (5.5, 6.5) and also for supporting the lower side of the fixed glass panels of the storey above.
 6. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 5, are characterized by the fact that, the uprights are not in contact with glass panels, their height is limited between the beams and they may be constructed of aluminum profiles or of sheet steel, such as IPE, U, Z or a hollow section etc.
 7. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 6, are characterized by the fact that, the structure of the curtain wall is rigid-stiff, and for their construction and for testing of their flexural stiffness a unitized system is applied, using prefabricated panels (4.1), filled in with cover and insulation materials (4.2, 4.3), as well as with stiff components (4.5), which are transferred to the works site and suspended from prefixed and adjusted attachments (4.4)
 8. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 7, are characterized by the fact that, there are no uprights in the region of the windows, while windows (5.5, 6.5) are suspended freely by means of double mutual hooks (6.9, 6.10), which exist, the one (6.9) on the upper horizontal beam-lintel (6.7) of the storey windows, belonging to the structure of the storey above, and the other (6.10) on the upper horizontal profile (6.11) of the frame of the window glass panels (6.5), terminating with the lower horizontal profile (6.12), at the lower horizontal beam-sill of the storey windows (6.6), where they are held firm there, in a manner ensuring that structure and windows (5.4 and 5.5) or (6.4 and 6.5) will constitute the fixed and unified sector of the storey (5.1, 6.1), which cooperates in its seismic performance with the respective sector of the storey above (5.2, 6.2) via the sliding line created between the double mutual hooks (6.9 and 6.10).
 9. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 8, are characterized by the fact that, the line of suspension of the windows constitutes also a line of division of the fixed sectors of the curtain wall, as well as a sliding line between them, with the insertion in-between the double mutual hooks of a gasket (6.3) of a material having low coefficient of friction, such as polyamide, teflon or other similar to ensure that the two fixed sectors will slide freely between them and thus ensuring a free and independent movement of the sector, which follows the displacement of the floor slab of the storey referred to (5.1, 6.1), from the sector above, which follows the displacement of the floor slab of the storey above (5.2, 6.2) where, at the same time the sliding line also serves as an axis of revolution of the hook (6.10) on (6.9) for the opening of the windows.
 10. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 9 are characterized by the fact that, the fixed panels (6.4) are also suspended by means of hooks, one of which (6.13) is provided throughout the length of the lower horizontal beam-sill of the storey windows (6.6) and the other (6.14) on the upper horizontal profile of the frame of fixed glass panels (6.15), and that the fixed glass panels terminate by the lower horizontal profile of their frame (6.16) at the upper horizontal beam-lintel of the windows of the storey below (6.7), which beam belongs to the structure of the storey referred to, and the fixed panels are fixed there by similar hooks, one of which (6.17) is provided throughout the length of the beam (6.7) and the other (6.18) on the profile of the frame of the fixed glass panel (6.16), and are held firm on both beams (6.6 and 6.7) by way of rubber inserts (6.19) having a high coefficient of friction, so that in combination with the joining of the upper horizontal section of the frame (6.15) with the horizontal sill-beam (6.6) by means of bolts at point (6.20), the fixed frame (6.4) is immobilized on the sill-beam (6.6).
 11. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 10, are characterized by the fact that, there are no uprights over the region of the windows, that the structure of each storey is confined only to the fixed part (spandrel) of the storey, on whose slab it is fixed and which slab it follows at all seismic displacement, and that fixed glass panels, along with all other facing material applied on the structure of the curtain wall remain steady in the course of the earthquake in relation with the storey slab on which they are fixed and also that all drifts (δ) between the storeys are dealt with and absorbed exclusively over the region of the windows (5.5, 6.5) of each storey.
 12. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 11, are characterized by the fact that, the relative drift (δ) between storeys, on one hand, in a direction perpendicular to the surface of the curtain wall (7.7), is absorbed through the joints provided at the window suspension hooks (6.9, 6.10) and also at the attachments connecting the windows to their horizontal sill-beam (6.22, 12.2, 12.3), as a result of the rotation margin allowed to the square headed bolt (12.2) at the angle (12.3) and also of the margin allowed to the bolt at the incision (12.6) of the section of the window frame (12.7), and on the other hand, in a direction parallel to the surface of the glass curtain wall, the relative drift (δ) (8.6) is transferred in a horizontal sense through the sliding line (2.3, 5.8, 6.8, 8.3) to the extremities of the glass curtain wall, where it is absorbed at the angle curtain walls, constituting the problem, by angle profiles and at the glass curtain wall of a single facing or a single plane, by profiles of side edge of a similar form.
 13. Earthquake resistant curtain walls with suspended glassed panels, in accordance with requirements 1 to 12, are characterized by the fact that the angles of the structure of the curtain wall are constructed by cutting the aluminum profiles of the horizontal beams (9.3) and (9.4) in the direction of the bisecting line of the angle formed (9.1, 9.2) and are joined firmly by means of tough parallel blades (9.5, 9.6), in a manner ensuring that the entire structure of the glass curtain wall in each storey, rectilinear and angular sectors, is unified and transferred in a single way, by following the displacements of the storey slab on which it is fixed.
 14. Earthquake resistant curtain walls with suspended glassed panels, in accordance with the requirements 1 to 13, are characterized by the fact that for the absorbtion of the conflicting relative drifts at the corner of a curtain wall an angle profile is used, which consists of to main inner legs (10.1), of an angle in proportion with the angle of the corner of the building and length in proportion of the drift (δ) which should be absorbed, in combination with the termination of the vertical section of the window frames culminating at the angle (10.6) so that always their overlapping will be maintained and also by parallel water tight legs (10.2) and (10.3) with water tight gaskets, which in combination with the terminations of profiles (10.7) and of glass panes (10.8) meet the water tightness requirements, before and after the earthquake.
 15. Earthquake resistant curtain walls with suspended glassed panels, in accordance with the requirements 1 to 14, are characterized by the fact that, the main legs of the angle profile (10.1) and of the frame terminations (10.6) are always overlapping, while, for dealing with the drifts along the diagonal of the building, the glass panes are chamfered at their edges (10.9), depending on their anticipated diagonal drift (6′) (10.10), in a manner ensuring that the glass panes will not collide with each other in the course of the earthquake.
 16. Earthquake resistant curtain walls with suspended glassed panels, in accordance with the requirements 1 to 15, are characterized by the fact that, to enable drifts in all directions to be absorbed, the angle profile has at its center a closed core (10.4), by means of which it is suspended (11.1) from the lower side of the two upper horizontal beams-lintel of the storey windows (11.2), by means of a small plate as attachment (11.3) and of a pin (11.5) with a play allowing the free movement of the angle profile at the top, according to the drifting of the structure of the glass curtain wall of the storey above (a gyroscopic movement), while its lower end, stands on the horizontal angle formed by the lower horizontal beams-sill of the storey (11.6) by means of an attachment having the form (11.7) and a pin (11.8) provided with the necessary play (11.9) allowing vertical movements and turns.
 17. Earthquake resistant curtain walls with suspended glassed panels, in accordance with the requirements 1 to 16, are characterized by the fact that, the seismic unification of the two parts of the fixed sector, both the structure and the windows, is achieved in various ways, depending on the condition of the windows before and during the earthquake, where, when windows remain closed, as in tall buildings, their stabilization on the sill (12.1) is obtained by means of screw (12.2) and angle with hole for screw (12.3), as well as fork (12.4) in collaboration with pin (12.5), of which the two first (12.2 and 12.3) hold and secure the windows against seismic forces perpendicular to the plane of the glass curtain wall, corresponding to the positive or negative wind pressures and, at the same time, they function as joints for absorbing relative drifts (7.1) and also by means of the attachments fork and pin (12.4 and 12.5), which bar all sidelong drifting of the windows in relation to the sill-beam (12.1).
 18. Earthquake resistant curtain walls with suspended glassed panels, in accordance with the requirements 1 to 17, are characterized by the fact that, corresponding to the attachments, fork and pin (12.4 AND 12.5), at the top of the window frames and at the points of the vertical joints attachments are fixed, U form plate (13.1) in collaboration with angle (13.2) which aim at operating in collaboration with the fork for maintaining firm and unvaried all vertical joints of the curtain wall grid (13.4), and they will also assist the unified operation of the fixed sector for absorbing the drift (δ) through the sliding line, either if the windows happen to be closed at the moment of the earthquake or if they happen to be open, and in parallel, they will hold firm the structure of the glass curtain wall, without any variation to its tightness and its mechanical performance, so that, after the earthquake, the curtain wall may resume its original condition.
 19. Earthquake resistant curtain walls with suspended glassed panels, in accordance with the requirements 1 to 18, are characterized by the fact that, when windows operate normally as projected ones, the unification of the two parts of the fixed sector is obtained, on the one hand, when windows happen to be closed at the moment of the earthquake, by putting in the place of the attachments instead of screw and angle (12.2 and 12.3), tough locks (14.1) with pin (14.2) which hold and lock the windows against seismic forces perpendicular to the plane of the glass curtain wall and, at the same time, to absorb all relative drifts (7.7), while in parallel the attachments fork and pin (12.4 and 12.5) bar all sidelong drifting of the windows in relation to the sill-beam (12.1), and on the other hand, when windows happen to be open at the moment of the earthquake, the unification of the two parts is obtained by means of brackets holding the windows open and locking them (14.1, 14.2), in combination with attachments (13.1 and 13.2), which are permanently held in place, irrespectively of the condition of the windows.
 20. Earthquake resistant curtain walls with suspended glassed panels, in accordance with the requirements 1, are characterized by the fact that, in the case of a curtain wall in which the glass panels are unified from one storey to another, or from floor to floor of the storey above or below, or from the floor to the roof of the same storey, the operation of the sliding line (2.3, 5.8, 6.8, 8.3) shall be valid in full, as long as the glass panel unified in height (16.1) operates as a fixed sector, as in cases (2.1, 5.1, 6.1), but in this case, the two horizontal beams (6.6 and 6.7) shall be unified into a single beam per storey (16.2), functioning at the same time as a sill (16.3) and a lintel (16.4) and having the glass panels suspended with the use of double mutual hooks (16.5) of identical form and method of operation as in the case of the windows, and the said single beam shall carry the same method of stabilization (16.6) to ensure the operation of the sliding line, with supports and dimensions of the various features corresponding to the structural and dynamic requirements of the project.
 21. Earthquake resistant curtain walls with suspended glassed panels, in accordance with the requirements 1 to 20, are characterized by the fact that, the dimensions of the aluminum profiles, the form of the panels, of the structure and of the glass panels, the supports and the method of fixing the uprights depend on the structural features of the project and on the architectural requirements of the construction. 